Method and apparatus for casting diamond studded tools



Feb. 1, 1944. R WILSON 2,340,785

METHOD AND APPARATUS FOR CASTING DIAMOND STUDDED TOOLS 3 Sheets-Sheet 1I Filed Nov. 4, 1941 INVENTORI Jfafier/ d fli/swt BY ATTORNEY Feb. 1,1944. R; G, MLSON 2,340,785

METHOD AND APPARATUS FOR CASTING DIAMOND STUDDED TOOLS Filed Nov. 4,1941 s She etsSheet 2 If INVENTOR.

., F050! 6. ikilsan A TTDIPNE Y Feb. 1, 1944. 5, WILSON 2,340,785

METHOD AND APPARATUS FOR CASTING DIAMOND STUDDED TOOLS Filed Nov. 4,1941 s Sheefs-Sheet s 1 z 3 ea 65 60 i 2 v 51 115 7 2 71 g az M 42 1/5 W11 l 1 s1 90 $1 I 117! K /J7/ $11 54 ,rr' w v 55 35 29 8 64 55 1&5 14155 I I a 117 3 1.9 4 18 22 4/ 20 52 INVENTOR.

. 1 5g 3050! [7. 55km ATTORNEY Patented Feb. 1, 1944 orrics METHOD ANDAPPARATUS FOR CASTING DIAMOND STUDDED TOOLS Robert G. Wilson, Brook]mesne assignments to Anton yn, N. Y., assignor, by Smit & Co. Inc.,

New York, N. Y., a corporation of New York Application November 4, 1941,Serial No. 417,861 13- Claims. (Cl. 22-43) This invention relates to animproved method and apparatus for casting diamond studded tools used fordrilling, boring, cutting and shaping rock, stone, metals and other hardsubstances.

Diamond studded tools have heretofore been made in which the diamonds orcutting stones are embedded in cast metal which forms the working end ofthe tool and which is shrunk or brazed onto a tool blank or shank. Inorder to produce a satisfactory tool of this character, it is importantthat the diamonds be tenaciously bonded and gripped by the cast metal sothat they will not loosen under severe use and that the cast met al besound throughout and free from blowholes or other lines or areas ofweakness.

In accordance with this invention a base molding die of the proper shapeand size to form the desired casting cavity is provided. The base diemember is provided with one or more openings extending therethrough eachof such diameter as to receive the selected cutting end of the diamondor cutting stone inserted therein. In forming core or drill bits whichare to carry a considerable number of diamond or bortz fragments in theworking end thereof, the pin-sized openings in the base die member areso arranged that when the inner ends thereof have received the diamonds,the diamonds will be arranged in the working face of the cutting toolalong generally radial lines.

Where a core bit is to be formed, a carbon core is provided which isseated over an enlarged opening in the bottom wall of the base die. Thecore is preferably hollow and may be provided with spaceddiamond-seating openings extending horizontally through the side wallthereof so that the diamonds may be set in the outer ends of theseopenings and thus provide reaming stones around the inner periphery ofthe workingend of the cast core bit.

The apertured base die is positioned over a suction cup and a suitablesuction pump is connected to the suction cup and operates to draw fromtwo to four pounds suction pressure through the apertured base die andcore. This suction is applied to the apertured base die and core "priorto the setting of the diamonds therein and the suction continuesuninterrupted until the molten casting metal has been poured. Thissuction facilitates the setting of the selected cutting points of thediamonds in the openings or apertures in the base die and core.

The tool blank or shank is mounted within a suitable collar member whichis positioned, to rest upon an upstanding shoulder of the base die.Suitable means, such as micrometer screws, extend through the walls ofthe tubular holder and are arranged to engage the blank or shank so thatthe lower end thereof may be accurately positioned and centered withrespect to the casting cavity in the base die. The continuing suctionexerted on the diamonds retains the diamonds firmly seated in the innermouths of the openings provided in the base die and carbon core.

The molten casting metal is then poured into or around the tool blank orshank,'which is so arranged with respect to the base die member that themolten metal may freely flow into'the casting cavity and around thesuction held diamonds supported upon the apertured base die member andapertured core. When sufficient molten casting metal has been pouredinto or around the tool blank or shank to fully fill the casting cavity,the suction is promptly cut off and the molten metal permitted to cooland harden. The lower end of the tool blank or shank may be providedwith slots, or notches to insure a firm bond between the blank or shankand the metal cast thereon.

The suction action, which continues until the metal has been poured,serves not only to firmly retain the diamonds in proper position in themold cavity and prevents movement or flotation thereof in the pouredmetal, but the suction draws the casting metal closely to the outersurface of the diamonds so that when cast the diamonds will be rigidlybonded to the cast metal with only the selected cutting points of thediamonds projecting from the working face of the tool. The suctionfurther operates to withdraw all the gas through the suction aperturesof the base die member and apertured core, so that a firm and soundcasting is produced which is free from blowholes, fissures, and otherundesirable lines or areas of weakness.

The apparatus is so formed that it can easily and quickly be taken apartwhen the cast metal has sufiiciently cooled. The same or identicalsuction cups may be provided to cast numerous different types of diamondstudded tools, and the suction cups can be mounted upon a table andconveniently spaced apart to provide ample room for the operator oroperators stationed at each suction cup. The suction' cups are connectedby suitable piping to the suction pump which may operate to supplysuction to any desired number of suction cups. A quick action cut-offvalve is provided in the branch suction line leading to each suctioncup, which permits the suction to be cut off promptly after the moltenmetal has been poured. It will be appreciated that if suction continuesto be applied after the metal has been poured an undesirable quantity ofcast metal will be drawn through the diamond-seating apa heavy steelsupporting ring which i snugly the suction cup but seated on the uperrim of is not secured thereto. The base die member has a laterallyextending flange which snugly seats on the supporting ring, and bymaking the laterally extending flanges of all of the various die membersemployed in casting various diamond tools of the same size and diameter,it will be appreciated that the same suction cup and supporting ring maybe used to support base die members of various shapes and forms forcasting various diamond studded tools. The holding collar has aninternal circular recess at its lower end shaped to embrace and snuglyseat over an upstanding shoulder formed on the base die member so thatthe inner surface of the upstanding shoulder of the die member and asection of the inner surface of the holding collar together provide amold wall which defines the outer surface contour of the cast metal. Thesame size holding collar may generally be employed for casting eithercore or drill bits having the same external diameter of workin head.Since the tool blank or shank is held to the holding collar by easilyadjustable micrometer screws, the tool blank or shank having the castmetal and diamonds associated therewith may be lifted oil from the basedie member and the completely cast tool easily removed from the holdingcollar by loosening the micrometer adjfusting screws. Any excess ofcasting metal may be removed from the external and internal surfaces ofthe tool by boring, grinding, or by shaping in a lathe.

An object of this invention is to provide an improved method of castingdiamond studded tools which can be economically and quickly per formedto produce tools in which the diamonds or cutting stones are seated inthe cast working face of the tool with great firmness and tenacity.

Another object of this invention is to provide improved apparatus forcasting diamond studded tools which is simple in construction andoperation, whose parts are adaptable to the manufacture of various typesand kinds of diamond studded tools, which can be easily and quicklyassembled before casting and disassembled after casting to permit quickand ready removal of the cast tools.

Another object of this invention is to provide improved apparatus forcasting diamond studded tools in which means are provided for insuringaccurate centering and positioning of the tool blank or' shank withrespect to the metal cast thereon to provide a tool which is true andefilcient.

Other objects of this invention will become apparent as the disclosureproceeds.

Although the novel features which are believed to be characteristic ofthis invention will be particularly pointed out in the claims appendedhereto, the invention itself, as to its objects and advantages, and themanner in which it may be carried out, may be better understood byreferring to the following description taken in connection with theaccompanying drawings forming a part hereof, in which Fig. 1 is aperspective view of a core bit made in accordance with the method andapparatus of this invention;

Fig. 2 is a vertical cross-sectional view through the core bit as itapears when looking in the direction of the arrows 2-2 of Fig. 1;

Fig. 3 is a perspective view of a drill bit which may be made inaccordance with this invention;

Fig 4 is a longitudinal cross-sectional view of the drill bit as itappears when looking in the direction of the arrows 4-4 of Fig, 3;

Fig. 5 is a front elevational view of the casting apparatus showing thecasting table having a plurality of spaced suction cups mounted thereon,one of the suction cups having the base casting die and holding collarmounted thereon and the other cups having only the base casting diemounted thereon, this view'showing the apparatus as it appears whenlooking in the direction of the arrows 5-5 of Fig. 6;

Fig. 6 is a top plan view of the casting apparatus illustrated in Fig.5;

Fig. 7 is a transverse cross-sectional view of the casting apparatus asit appears when looking in the direction of the arrows 1--1 of Fig. 6;

Fig. 8 is an enlarged vertical cross-sectional view through theassembled suction cup, base die, carbon core and holding collar used forcasting a core bit of the type illustrated in Figs. 1 and 2, and as theyappear when viewed along lines 88 of Fig. 6; and

Fig. 9 is an enlarged vertical cross-sectional view of the assembledbase die and holding collar for casting a drill bit of the typeillustrated in Figs. 3 and 4.

Similar reference characters refer to similar parts throughout theseveral views of the drawings and the specification.

While it will appreciated that my improved method and apparatus may beemployed for casting various shapes and types of diamond studded tools,to more clearly illustrate the method and apparatus there is shown inFigs. 1 and 2 one type of core bit and in Figs. 3 and 4 one type ofdrill bit, which may be made by following the teachings of the methodand apparatus disclosed in this application. It will therefore beunderstood that the core bit and drill bit are shown in Figs. 1 to 4 forillustrative and explanatory purposes only, since the method andapparatus which constitute this invention are not limited to the castingof only this particular core bit and drill bit as illustrated but may beemployed in the casting of various shapes and types of diamond studdedtools.

' The core bit shown in Figs. 1 and 2 for purposes of illustration, isformed from a steel blank I of tubular form having a threaded shankportion 2 provided with strong external threads 3 so that the bit may befirmly secured to the drill rod.

The shank has an enlarged body portion 4 provided with a top shoulder 5against which the end of the drill rod seats; The lower end of the shankhas a reduced leg portion 6 defining an external circular recess 1. Thele portion 6 is perforated by a plurality of spaced round holes 8 whichlead into slots 8' which extend to the lower edge of the leg portion.The round holes 8 and slots 8' will hereafter be referred to as bayonetslots. The leg portion 6 of the blank may be provided with any desirednumber of conveniently spaced bayonet slots designed to permit themolten bit metal which is to form the working end. of the bit to flowtherethrough andlock the end of the cast bit to the blank.

The working end 9 of the bit is cast to the lower end of the bit blankand when formed defines a circular collar H) which fillsthe externalrecess '1 at the lower end of the bit blank. The lower working face ofthe casting. 3' preferably has an arcuate contour l i in which-thediamonds D are partially embedded but have their sharp points protrudingso as to grind away the rock or material being cored. It will be notedby referring more particularlyto Fig. 1 that the diamonds D arepreferably arranged on the working end ot the bit in radial rows so asto provide passages between the diamond rows through which water orother liquid may move during the coring operation. It will also be notedthat the ends of the diamond rows extend well into the inner peripheryand into the outer peripher of the working face of the bit so as toinsure sufficient reaming of both the periphery of the hole being boredand the core being formed, so that the metal parts of the bit may berotated during the coring operation without excessive friction or wearbetween the metal parts of the bit and the rock being cored. Theinterior surface 12 of the bit is truly cylindrical and presents asmooth wall except where the marginal diamonds project. The outersurface I3 of the bit is also truly cylindrical and presents a smoothwall except where the peripheral diamonds project. Waterways are formedby providing vertical shallow grooves M in the outer cylindrical surfaceof the bit body which lead to radial grooves It in the working face ofthe bit.

The drill bit illustrated in Figs. 3 and 4 is formed from a steel blankI of tubular form of the proper size and shaped similarly to the blankforming a part of the core bit above described. The working end E5 ofthedrill bit is cast to the bit blank and when formed provides a circularcollar 56 which fills the external circular recess 1 at the lower end ofthe bit blank. The molten casting metal also fills the lower end of theblank to provide a cast metal bottom wall H which has a concave workingface 13 surrounded by a convex working rim H9. The diamonds D are set inthe concave working face l8 and in the convex working face of the rimIll. The molten coating metal flows through the bayonet slots in the legportion 6 of the blank, thus firml locking the cast bit metal to the legportion 6 of the blank. The exterior surface 23 of the bit as formed istruly cylindrical and presents a smooth cylindrical wall except wherethe marginal diamonds project. A vertical water hole 24 is cast in thebottom wall I! of the bit and the rim portion l9 may be provided withshallow radial water grooves 23 which lead into vertical water grooves22 in the cylindrical outer surface oi the bit.

The cast metal from which the working end of the tools is made maycomprise a metallic alloy which is tough, strong and resistant to wear,and of such a character that it can be reduced to molten form forpouring into the casting cavity.

The apparatus employed for casting the tools is illustrated moreparticularly in Figs. 5 to 9 inclusive and comprises a series of molds-25 which are positioned in convenient spaced relationship on a steeltable 26 having supporting legs 27. The construction of the mold forforming the core bit above described is illustrated in Fig. 8 and themold for casting the drill bit above described is illustrated moreparticularly in Fig. 9. The same general apparatus is used for cast-'ing various types of diamond studded tools and comprises a suction cup28 of circular form which may be shaped from a solid steel casting whichrests on the table 23. The suction cup 28 has a concave suction chamber29 therein of generally saucer-shaped form and its vertical wall 30 isprovided with a circular recess 3i which supports a heavy steelmold-supporting ring 32.

The bottom wall 33 of the suction cup is provided with a threadedopening 34 into which the threaded end of the downwardly extending steelsuction pipe 35 is threaded. Each suction pipe 35 is connected to ahorizontally extending suction pipe 36 positioned under the table top 25by means of a coupling 31, as shown more particularly in Fig. '7. Ariser suction pipe 38 is connected to the horizontal suction pipe 36 bya coupling 39, and the upper end of the riser pipe 38 is connected to ahorizontally extending branch suction pipe 40 at the back edge but abovethe top of the table 26 by a coupling 4i. Each of the branch suctionpipes 40 is connected to a main suction line 42 which extends parallelto the table length by a coupling 43. The main suction line 42 isconnected to a suction pump 44, which may rest on the floor, by adownwardly extending main suction line 45. The suction pump 44 is drivenby a motor 43 with a power switch box 41 conveniently located adjacentthe table. A quick acting suction control valve 48 is located in eachriser pipe 38 adjacent the rear edge of the table.

Where the suction pump 44 is connected to a plurality of suction cups28, uniform suction pressure on each cup can be maintained by insertinga suction regulator valve 49 in each of the branch suction pipes 43. Anair filter 49' is also preferably provided to prevent particles of castmetal from being drawn into the suction pump 44. Theair filter may beconveniently inserted in main suction line 45.

The steel base die for casting the desired tool has a laterallyextending circular flange 5! which seats snugly within a circular recess52 formed in the heavy supporting ring 32, as shown more particularly inFig. 8. In casting core bits for example. the bottom die 51) is providedwith a cylindrical external wall 53 which extends downwardly into theenlarged circular opening 54 formed in the supporting ring 32. Anannular bottom forming wall 55 extends horizontally inwardly from thedownwardly projecting cylindrical wall 53 and a short internal riserwall 53 of cylindrical. form extends upwardly from the annular bottomforming wall 56.

A steel holding collar 53 of cylindrical form has its lower end 3!resting on the flange 5! of the base die 5% and is also provided with aninternal recess 52 which snugly seats over the top edge of a shortexternal riser wall 53 which forms a rising continuation of the externalwall 53. The lower body portion of the holding collar has an internalcylindrical recess M which shapes a part of the external cylindricalsurface of the cast working end of core bit. The upper end portion. ofthe hold ng collar to is internally threaded at 55 to receive thethreaded portion 2 of the shank l of the core bit. It will be noted thatthe internal threads 53 on the upper body portion 65 of the holdingcollar are so formed as to have a rather loose threaded connection withthe external threads 3 on the upper threaded portion of the bit shank I,so as to permit micrometer adjustment of the lower end of the externalcorner 80 of bit shank I with reference to the casting cavity 51 in thebase die plate 58.

A hollow carbon or graphite core is positioned Within the bit shank Iand comprises a cylindrical side wall 1| and a top Wall 12, defining ahollow interior 13. The side Wall 1| has a laterally extending collarportion 14 formed integrally therewith whose flat horizontally extendingtop surface is substantially in line with the adjusted lower edge of theleg portion 6 of the bit shank. The lower horizontal wall 16 of thecollar portion 14 is designed to seat on the flat upper edge of theinternal riser wall 56 of the bottom die plate 58. The lower end 11 ofthe side wall 1| seats within the circular hole 18 in the base die plate58 and against the internal cylindrical face of the riser wall 56. Thusthe carbon core 18 firmly seats on the riser wall 56 but is not securedthereto.

The bit shank is so adjusted that the lower internal corner 2| of theleg portion 6 of the bit shank I is positioned closely adjacent theupper the core body 14, with the cylindrical internal surface I2 of thebit shank in accurate alignment with the vertical external surface 81 ofthe internal riser wall 56 of the die plate 58.

Accurate alignment of the internal cylindrical surface |2 of the bitshank I with respect to the external surface 81 of the die plate riserWall 56, is effected by four finely threaded adjustment screws 83 whichare threaded into corresponding threaded openings in the lower portionofv the side wall of the holding collar 68. The inner ends 85 of thescrews 83 are arranged to abut the external cylindrical surface of thebody portion 4 of the bit shank I. By proper adjustment of the settingscrews 83 the lower end of the bit shank can be swung a limited extentto a position where the internal cylindrical surface I2 thereofaccurately aligns with the external cylindrical side wall surface 81 ofthe riser wall 55. The extent of the adjustment required to effectaccurate and true alignment of the internal cylindrical surface I2 ofthe bit shank with the external cylindrical surface 81 of the riser wall56, will be visibly indicated to the operator when he looks down intothe bore of the shank I.

The hull nosed end of the core bit is shaped by the arcuate contour ofthe inner bottom face 86 of the annular bottom wall 55 of the die plate58, the internal cylindrical face of the core bit is shaped in part bythe inside face 81 of the internal riser wall 56 of the bottom die plate50 and in part by the external cylindrical wall 8| of the core, and theexternal face of the bit is shaped in part by the inside vertical face88 of the peripheral walls 53 and 63 of the bottom die plate 58 and inpart by the inside cylindrical face 89 of the holding collar 60.

The annular bottom forming wall 55, the downwardly extending outer wall53 and the inner riser wall 56 of the bottom die plate 58 is puncturedby a series of pin-sized suction openings or ports 98 which may extendat various angles and preferably are arranged along radial lines. Thediamonds D are seated in the internal ends of the suction openings 98,

The hollow carbon core 18 is also provided with one or two rows ofpinhole suction openings or ports 9| which extend generally horizontallythrough the collar portion 14 of the carbon core 10. Diamonds D areseated in the external ends of the horizontally extending suction ports9| in the carbon core.

It will be noted that the diamonds D are s t directly over the mouth ofthe suction ports 88 and 9| and are held in place by suction exerted bythe suction pump 44 only without the use of other diamond holdingdevices. The suction force draws the air from the interior of thecasting chamber 51 through the ports 9| in the carbon core and throughthe ports 90 in the die plate 58, through the suction cup 28 and outthrough the suction pipe 35.

The mold for the drill bit illustrated more particularly in Fig. 9comprises a bottom die plate I08 formed of steel which has the usualflange 5| seating within the recess 52 of the steel supporting ring 32,and also has a downwardly extending cylindrical casting wall 53 and ashort upwardly extending riser wall 63 whose inside face 88 forms inpart the external cylindrical surfac of the cast working end of the bit.The holding collar 68 has its lower end 6| seating on the flange 5| ofthe base die I88 and is provided with the internal groove 62 which seatson the external riser wall 63 of the die plate I88.

The bit shank I, having the threaded stem portion 2 andenlarged bodyportion 4, is loosely threaded into the holding collar 58. Themicrometer adjusting screws 83 are provided to align the lower end ofthe bit shank, The casting metal 8 is poured into the bit shank I andflow freely into the mold cavity I I I and through the holes 8 in thebit shank.

The bottom wall of the die mold I88 has a concave rim-forming portion I8| and a convex center portion I02. A large number of rather closelyspaced pinhole openings or ports I 03 extend in radial rows through theconcave rim-forming portion |0|, and the convex center portion I82 andthe cylindrical casting wall 53 of the die plate I 00. A carbon pin I85may be set into the shank and the lower end of the pin is shaped to restupon the concave bottom wall portion |8| of the die mold I88 so as toprovide a Water hole 24 for the bit. The pin is held in erect postion bythe suction exerted through the suction openings I03 beneath the pin.

In order that the micrometer screws 83 may properly perform theirfunction of centering the tool shank over the casting cavity in the dieplates 58 or I88, it will be appreciated that the holding collar 68 mustbe held immovable and accurately Seated on the die plate. This resultcan be obtained by providing a laterally extending flange section I I 5on the lower end of the holding collar 60, which flange section H5snugly rests on the flange 5| of the die plate. Three equally spacedmetal tapering pins ||6 are driven into aligned openings 1 and H1 in theflanges H5 and 5| respectively, which keys are easily removable and yetserve to firmly and accurately retain the holding collar 68 accuratelycentered with respect to the casting cavity in the die plate.

The method of casting the diamond studded tools is substantially thesame for all such tools to be formed. To facilitate description theprocess of casting Will be described more particularly in reference tothe core bit illustrated in Figs. 1

and 2.

In casting the core bit the bottom die plate 58 is placed on thesupporting ring 32 and the carbon core 18 placed in seating position onthe riser wall 56 of the die plate 58. The suction pump is put intooperation so as to draw atmospheric gas or air through the suction ports98 and 9|, at two to four pounds suction pressure. The selected sharppoints of the diamonds D are set directly into the mouth of the ports 99and 9 I, which diamond placing operation is facilitated by the suctionwhich helps to draw the diamonds into the ports and hold them inposition. The diamond setting operation can generally be performed inten to twenty minutes by a skilled operator.

The proper holding collar 6B and bit shank l is then selected and thethreaded portion 2 of the bit shank is screwed into the holding collar60, which provides a rather loose threaded connection. The holdingcollar 5% with the bit shank l is then placed upon the bottom die plate5% and the tapering pins i it are driven into the aligned openings H1and ill so as to rigidly secure the collar 60 in the proper die castingposition.

The lower end of the bit shank l is then adjusted by the four micrometerscrews 83 so as to bring the inner cylindrical wall 52 of the bit shankinto accurate and true alignment with the inside face 8'1 of theinternal die wall 5%. The inner corner edge 2! of the bit shank is alsoscrewed down so as to seat closely adjacent the outer corner 85 of thecollar portion M of the core. The suction continues to hold the diamondsD in place during placement of the collar 66 and bit shank l inposition.

With the full two to four pounds suction continuing, which pressure isregulated by suction regulator valve 49, the molten casting metal ispoured into the interior of the bit shank l, which itself serves as apouring flask, and the metal flows into the molding cavity until themolten metal has risen in the bit shank i to a point where the holes 8are covered with molten metal. The suction is continued with full forceduring the pouring operation. The suction, however, is cut off promptlyafter pouring by manipulating the cut-01f valve it. It is important thatthe suction be cut off promptly after pouring or the poured metal willcontinue to be sucked through the ports 99 and Si. The air filter 49',however, prevents any particles of metal from being drawn into thesuction pump 44 which particles might otherwise damage the pump.

The suction ports 90 and ti accomplish three purposes; first, they holdthe diamonds rigidly in the mouth of the ports so that they are at alltimes in proper position and are not disturbed during the adjustment ofthe bit shank l in position and during the pouring and hardening of themolten metal; second, the suction is sufiicient to draw the metalcompactly around each of the diamonds so that a firm diamond setting issecured; and, third, the suction draws out the molding gases and insuresa sound and dense working end casting.

As soon as the metal is sufiiciently cooled, the holding collar Fill anddie plate 56 is lifted cfi from the ring 32. The keys US are driven out,the core pushed out, and the base die is removed from the holding collarand cast bit. The set screws 83 may then be loosened and the holdingcollar 66 screwed off from the bit shank I.

It will be found that a small amount of metal may have been drawnthrough the ports 98 and Si and has dropped down into the interior ofthe suction cup 28, which can be recovered and remelted. Also, stringsof metal formed by the ports 90 and 9! may project from the end of thebit, which can be broken oif or they may be left in the ports St and 91where they can be easily pricked out by a pricking tool. The cast bit asformed requires very little machining. There may be some metal depositedon the inside cylindrical surface E2 of the bit shank which can bequickly cut oif on a lathe or a grinder and the outer peripheral surfaceIt of the cast bit end 9 may also be ground smooth with the outercylindrical surface of the body portion i.

The drill bit is made by the same operations .as the core bit, exceptthat a drill bit die N30 is positioned on the steel supporting ring 32.The diamonds D are set into the mouths of the ports its and the carbonpin i be isplaced in position. The lower end of the carbonpin maybeground to conform to the inner contour of the concave bottom wallportion it! of the die plate It'd, so that the carbon pin it? is alsoheld .in erect position the suction ports positioned therebeneath.

After the diamonds have been set, the holding collar 69 is secured ontothe bit shank l and this assembly is positioned on the base plate H30and is properly centered by the keys it. The micrometer screws 83 permitthe operator to properly align the bit shank i with respect to thecasting cavity.

With the suctionstill applied, the molten metal He is poured into theshank i until the metal rises well above the holes 8 in the leg portion6 of the bit shank. The suction is then cut ofi and the cast bit isremoved from the die plate-l E10 and the holding collarilt.

The carbon pin lot is then driven out and excess metal can be easilybored or reamed out of the interior of the bit shank i so as to providea smooth and siightly concave bottom i 1 l. The outer peripheral surface26 of the working end it may be cut or ground to present a smoothsurface which aligns with the cylindrical periphcry of the body portion3 of the bit shank l.

The apparatus for casting diamond studded cutting tools herein describedis readily adaptable and interchangeable for the manufacture of variousdifferent types of diamond studded tools. The suction cups 28 may beconveniently arranged on the casting table 2% so that several operatorsmay be employed simultaneously or so that the diamonds may be set in one:base die member while metal is being poured into another mold or whilethe poured metal is cooling in still another mold. For example, whilemetal is being poured or is cooling in the mold stationed at a, as shownin Figs. 5 and 6, the operators maybe placing diamonds in the ports ofdie plate 50 stationed at b and in the ports of the-die plate I00stationed at c.

. The suction cups are all connected to a single suction pump M designedto draw from two to four pounds suction pressure and each branch suctionline is leading to the individual suction cups is provided withconveniently located cutoff valve so that the suction pressure may bepromptly cut on immediately after pouring of the cast metal. It will beappreciated that the same suction cup 23 and the same supporting ring 32may be used to support a number ofdifferent base die members and shanksupporting collars. Thus a number of tools of different shapes may becast on the same working table by providing only a base die memberforeach tool to be cast and, if necessary, the proper shaped It will befound that the same size use of the same holding collar 6%, butobviously a different holding collar will be required for the casting ofdiiferent sizes of core-or drill bits.'

It will thus be appreciated that only 'three dif- .ferent kinds ofinterchangeable parts are required for casting numerous different typesand kinds of diamond studded tools; namely, base die members in therequired sizes and shapes, carbon cores in the required sizes andshapes, and holding collars in the required sizes and shapes. Thus aminimum of equipment is required for the casting of numerous differentdiamond studded tools.

It will further be appreciated that the operating parts may be quicklyassembled before pouring of the metal and quickly disassembled to permiteasy removal of the cast tool. The supporting ring 32 is unattached tothe rim portion of the suction cup 28 and readily lifts off. The basedie member also readily lifts off from the supporting collar 32 when thekeys I I6 are removed. The base die member can be easily pulled off fromthe cast end of the tool as soon as the cast metal has cooledsufficiently to permit handling thereof. The completely cast tool needthen only be removed from the holding collar 60 by loosening themicrometer screws 83. Since the threaded connection between the bitshank and holding collar 60 is very loose these parts can be easilyunscrewed and separated by a simple turn of the hand.

The contacting surfaces between the supporting ring 32 and the rimportion 30 of the suction cup 28 and the contacting surfaces between thesupporting ring 32 and the flange portion of the base die member, aresmoothly ground and fitted so that there is substantially no leakage ofair or atmospheric gas therebetween. The sealing effect can be furtherenhanced by oiling the contacting surfaces. There is thus substantiallyno loss of suction pressure except the necessary suction which draws theatmospheric air or gas through the diamond holding suction openings.

By continuing the suction pressure from the very beginning to the end ofthe casting operation, the diamonds or cutting stones are not onlyfirmly held in place during setting of the diamonds in the mouths of thesuction openings but the arranged position of the diamonds is in no waydisturbed when the holding collar and tool blank or shank is placed inposition. The continuing suction not only withdraws all gases from thecast metal during pouring so that a sound and dense casting is assured,but the suction serves the additional important function of drawing thecast metal firmly around the surfaces of the seated diamonds so that thediamonds are firmly and tenaciously locked in the cast metal.

While certain novel features of the invention have been disclosed andare pointed out in the annexed claims, it will be understood thatvarious omissions, substitutions and changes may be made by thoseskilled in the art without departing from the spirit of the invention.

What is claimed is:

1. An improved method of forming cutting tools characterized by cuttingstones bonded to the tool shank by cast metal, which method comprises,providing a stationary base die member having stone receiving openingsin the cavityforming wall thereof, drawing atmospheric gas through saidopenings, positioning cutting stones in the cavity ends of said openingsduring continuance of said suction pressure, positioning the tool shankover said suction cavity and adjusting the lower end of said tool shankwith respect to the casting cavity during continuance of said suctionpressure, pouring molten metal into the casting cavity between the lowerend of the tool shank and the cutting stones positioned therein duringcontinuance of said suction pressure, and promptly releasing saidsuction pressure immediately upon completion of the metal pouringoperation.

2. An improved method of forming cutting tools characterized by cuttingstones bonded to the tool shank by cast metal, which method comprises,providing a stationary base die member having stone seating openings inthe cavityforming wall thereof, drawing atmospheric gas through saidopenings at from two to four pounds suction pressure, positioningcutting stones in the cavity ends of said openings during continuance ofsaid suction pressure, positioning the tool shank over said suctioncavity and adjusting the lower end of said tool shank with respect tothe casting cavity during continuance of said suction pressure, pouringmolten metal into the casting cavity between the lower end of the toolshank and the cutting stones positioned therein during continuance ofsaid suction pressure, until said casting cavity has been filled withmolten metal, and promptly releasing said suction pressure immediatelyupon completion of the metal pouring operation.

3. An improved method of forming drill bits characterized by cuttingstones bonded to the tool shank by cast metal, which method includes,providing a stationary base die member having stone-seating openingsextending through the cavity-forming walls thereof, drawing atmosphericgas through said openings at from two to four pounds suction pressure,positioning cutting stones in the cavity ends of said openings duringcontinuance of said suction pressure, positioning the tool shank oversaid suction cavity and adjusting the lower end of said tool shank toalign the tool shank with respect to said casting cavity duringcontinuance of said suction pressure, pouring molten metal into thecasting cavity between the lower end of the tool shank and the cuttingstones positioned therein during continuance of said suction pressure,and promptly releasing said suction pressure immediately upon thecompletion of the metal pouring operation.

4. An improved method of forming core bits characterized by cuttingstones bonded to the tool shank by cast metal, which method includes,providing a stationary base die member having stone-seating openingsextending through the cavity-forming walls thereof, positioning a hollowcarbon core having radial stone-seating openings extending through itswalls centrally on said base. die member, drawing atmospheric gasthrough the openings in said base die member and carbon core at from twoto four pounds suction pressure, positioning cutting stones in thecavity ends of said openings during continuance of said suctionpressure, positioning the tool shank over said suction cavity andadjusting the lower end of said tool shank to align the tool shank withrespect to said casting cavity during continuance of said suctionpressure, pouring molten metal into the casting cavity between the lowerend of the tool shank and the cutting stones positioned therein duringcontinuance of said suction pressure until said casting cavity has beencompletely filled with molten metal, and promptly releasing said suctionpressure immediately upon the completion of the metal pouring operation.

5. An improved apparatus for casting cutting tools characterized bycutting stonesbonded to an externally threaded tool shank by cast metal,

said apparatus including, a suction cup, means for applying suction tosaid suction cup, a base die member seated on said suction cup having acasting cavity formed therein, diamond-seating openings extendingthrough the cavity-forming wall of said die member and leading to saidsuction cup, a holding collar seated on said base die member having aninternally threaded opening into which the tool shank may be inserted,the internal threads on said holdingcollar being so constructed andarranged as to provide a loosely threaded connection with the externalthreads on the tool shank whereby said tool shank is loosely supportedby said holding collar, and adjustable means associated with said collarfor adjusting said shank with respect to the casting cavity toaccurately align said shank with respect to the casting cavity.

6. An improved apparatus for casting core bits characterized by cuttingstones bonded to the tool shank by cast metal, said apparatus including,a suction cup, a ring member supported on the rim of said suction cupand having a central opening communicating with the suction cavity insaid suction cup, means for applying suction to said suction cup, a basedie member having a peripheral flange seated in a receiving recessformed in the inner rim of said ring member, said base member having acasting cavity formed therein, a hollow carbon core centrally supportedon said base die member, diamond-seating openings extending through thecavity-forming wall of said die member and the walls of said carbon coreleading to said suction cup, a holding collar seated on said base diemember into which the tool shank may be inserted, and adjustable meansassociated with said collar for adjusting said shank with respect to thecasting cavity to accurately align said shank with respect to the casing cavity.

7. An improved apparatus for casting cutting tools characterized bycutting stones bonded to the tool shank by cast metal, said apparatusincluding, a suction cup, a suction pump adapted to develop two to fourpounds suction pressure connected to said suction cup, a supporting ringsnugly seated on the upstanding rim of said suction cup, a base diemember snugly seated on said supporting ring and having a casting cavityformed therein, diamond-seating openings extending through thecavity-forming wall of said die member and leading to said suction cup,a holding collar seated on said base die member for loosely supportingthe tool shank over said casting cavity, a riser wall and a cooperatingreceiving recess associated with said holding collar and die member forcentering the holding collar on said die member, and adjustable meansassociated with said collar for adjusting said shank with respect tosaid casting cavity to accurately align said shank with respect to thecasting cavity.

8. An improved apparatus for casting cutting tools characterized bycutting stones bonded to the tool shank by cast metal, said apparatusincluding, a suction cup, a suction pump adapted to develop two to fourpounds suction pressure, suction piping connecting said pump to saidsuction cup, a suction cut-ofi valve in said piping adjacent saidsuction cup, a supporting ring snugly seated on the upstanding rim ofsaid suction cup, a base die member snugly seated on said supportingring and having a casting cavity formed therein, radially arrangeddiamond-seating openings extending through the cavity-rouning wall ofsaid die member and leading to said suction cup, a holding collar seatedon said base die member for loosely supporting the tool shank over saidcasting cavity, removable key elements for removably securing saidcollar member on said base die member and for centering said holdingcollar on said base die member, and aplurality of adjustable micrometerscrews associated with said collar and adapted to engage said shank foraccurately aligning said shank with respect to'the casting cavity.

9. An improved apparatus for casting cutting tools characterized bycutting stones bonded to the tool shank by cast metal, said apparatusincluding, a suction cup, means for applying from two to four poundssuction pressure to said suction cup, a base die member seating on saidsuction cup and having a casting cavity formed therein, a centralaperture in said base olie'mem'- her, a hollow carbon core having ashoulder portion seating on the peripheral rim of said aperture and aflange portion extending into said aperture, diamond seating openingsextending through the cavity forming wall of said die member and leadingto'said suction cup, diamond seating openings extending through theperipheral Wall of said core and communicating through the hollowinterior thereof with said suction cup, a holding collar seated on saidbase die member for supporting the tool shank over said casting cavity,and a plurality of adjustable micrometer screws associated with saidcollar and adapted to engage said shank for accurately aligning saidshank with respect to the casting cavity.

10. An improved apparatus for casting cutting tools characterized bycutting stones bonded to the tool shank by cast metal, said apparatusincluding, a suction cup, means for applying from two to four poundssuction pressure to said suction cup, a removable supporting ring snuglyseated on the upstanding rim of said suction cup, a removable base diemember snugly seating on said supporting ring and having a castingcavity formed therein, a central aperture in said base die member, ahollow carbon core having a shoulder portion seating on the peripheralrim of said aperture and a flange portion extending into said aperture,diamond seating openings extending through the cavity forming wall ofsaid die member and leading to said suction cup, diamond seatingopenings extending radially through the peripheral wall of said core andcommunicating through the hollow interior thereof with said suction cup,a holding collar seated on said base die member for supporting the toolshank over said casting cavity, and a plurality of adjustable micrometerscrews associated with said collar and adapted to engage said shank foraccurately aligning said shank with respect to the casting cavity.

11. An improved apparatus for casting core bits characterized by cuttingstones bonded to the tool blank by cast metal, said apparatus including,a suction cup, means for applying from two or four pounds suctionpressure to said suction cup, a removable supporting ring snugly seatedon the upstanding rim of said suction cup, a removable base die membersnugly seated on said supporting ring having a rim-forming castingcavity formed therein, said casting cavity including a depressed annularbottom-forming wall having an arcuately curved internal casting surface,an internal upstanding forming wall defining the inner periphery of saidcasting cavity and an upstanding forming wall defining the externalperiphery of said casting cavity, and a central opening in said base diemember defined by said inner upstanding wall, a removable hollow carboncore seating on said internal upstanding wall, a plurality ofdiamond-seating openings extending through the cavity-forming bottomwall, the internal peripheral wall and the external peripheral wall ofsaid base die member and through the peripheral wall of said core andleading to said suction cup, and a removable holding collar seated onthe upstanding wall 'of said die member for supporting the tool shank inposition over said casting cavity.

12. An improved apparatus for casting core bits characterized by cuttingstones bonded to the tool blank by cast metal, said apparatus including,a suction cup, means for applying from two to four pounds suctionpressure to said suction cup, a base die member seated on said suctioncup, said die member having a supporting flange portion, a centralaperture and a casting cavity positioned between said central apertureand said flange portion, said casting cavity being defined by adepressed annular bottom wall portion, an internal cylindrical rimportion and an external cylindrical rim portion rising above said bottomwall portion, a hollow carbon core having a cylindrical side wall and aclosed top wall, said cylindrical side wall having an enlarged bodyportion adapted to seat on the internal cylindrical side wall portion ofsaid die member, a plurality of radially arranged diamond-supportingsuction openings extending through the bottom wall portion and throughthe internal and external side wall portions of said casting cavitycommunicating with said suction cup, laterally extendingdiamond-supporting suction openings extending through the enlarged bodyportion of said core and communicating with the hollow interior thereof,and a holding collar seated on the external side wall portion of saiddie member for supporting the tool shank in position over said castingcavity.

13. An improved apparatus for casting core bits characterized by cuttingstones bonded to the tool blank by cast metal, said apparatus including,a suction cup, means for applying from two to four pounds suctionpressure to said suction cup, a removable supporting ring snugly seatedon the upstanding rim of said suction cup, a removable base die member,said die member having a flange portion snugly seating on saidsupporting ring, a central aperture and a casting cavity positionedbetween said central aperture and said flange portion, said castingcavity being defined by a depressed annular bottom wall portion, aninternal cylindrical rim portion and an external cylindrical rim portionrising above said bottom portion, a hollow carbon core having acylindrical side wall and a closed top wall, said cylindrical side wallhaving an enlarged body portion removably seated on the internalcylindrical side wall portion of said die member, a plurality ofradially arranged diamond-supporting suction openings extending throughthe bottom wall portion and through the internal and external side wallportions of said casting cavity communicating with said suction cup,laterally extending diamond-supporting suction apertures extendingthrough the enlarged body portion of said core and communicating withthe hollow interior thereof, and a removable holding collar seated onthe external side wall portion of said die member for supporting thetool shank in position over said casting cavity.

ROBERT G. WILSON.

